1. Field of the Invention
The present invention relates to energy efficient fans and, more particularly, to an energy efficient fan having one or more fan blades fixed to a hub which is freely rotatable relative to a central drive shaft, and wherein twirling of the hub creates angular momentum of the fan blade which carries the blade through a continuous 360xc2x0 rotational motion, thereby pushing a current of airflow.
2. Discussion of the Related Art
Motorized fans of various types are well known in the art. Typically, a hub is fixed to the end of a shaft which is rotatably driven by a motor. Several fan blades are fixed to the hub and pitched at an angle to move air as the hub and blades rotate. The amount of power required to drive the shaft and rotate the hub and blades at a specific RPM is primarily dependent on the size of the blades (i.e. surface area and length) as well as the pitch of the blades. More specifically, a significant amount of electrical energy is required to overcome the torque which is generated by the resistance of the fan blades when rotating, particularly at higher speeds. For this reason, the operation of electrically powered motorized fans, particularly those having a relatively large fan blade length or radius, can be costly when operating at higher RPMs. Accordingly, there remains a need in the fan art for an energy efficient fan which rotates one or more fan blades at a high RPM while consuming less energy than conventional motorized fans.
According to the present invention, one or more fan blades are fixed to a hub which is freely rotatable relative to a main drive shaft. In one embodiment, the inner circumference of the hub is greater than the outer circumference of the drive shaft so that when the shaft is moved in a cyclical motion, and the central longitudinal axis of the shaft travels through a continuous orbital path, the hub moves in a twirling action about the shaft. As the hub twirls, a weighted distal end of the blade travels through an arcuate path to generate angular momentum which is sufficient to carry the blade through an uninterrupted rotational motion, thereby resulting in rotation of the one or more fan blades. The fan blade is structured and disposed to push a large volume of air as it rotates, thereby creating a steady current of airflow with minimal energy consumption.